\begin{abstract}
In large classes, grading quality suffers as TA's and professors cannot 
easily spend time grading each paper.  Peer grading (non-anonymous) is one solution, 
but can be extremely biased and unreliable. If assignments are 
entirely peer-graded, then grades will quickly inflate as students 
realize it is mutually beneficial to give high grades.  

On the other hand, if grading is anonymous, expert (TA or professor) grading is 
inserted unpredictably, and students are graded on their grading 
abilities (relative to grades which also receive a grade from an 
``experts'' then a more effective grading system will result.

This paper proposes an anonymous grading system called CLAPTRAP in which 
peers and ``trusted'' graders (TA's or professors) anonymously grade a 
subset of assignments.  Students give their own assignments a grade as 
well.  A reputation mechanism maintains
a reputation score that reflects students' quality of grading.  
``Trusted'' grades are used
as a baseline for comparison to determine the quality of grading and reputation that will be earned.
The final grade for each student's assignment is an average of the given grades, weighted by the 
reputation of each individual grader. Because a student's reputation can be affected by the grade they
give themselves and the grades they give others, students have an 
incentive to accurately grade both their own papers and others' papers.

This paper also details a real-world implementation of the 
system described, which is presented alongside this paper as 
a proof-of-concept and prototype for users interested in future implementations.
\end{abstract}
